Directional growth of Cu3Sn at the reactive interface between eutectic SnBi solder and (1 0 0) single crystal Cu

The growth mechanisms of Cu3Sn at the interface between eutectic SnBi solder and Cu were investigated by transmission electron microscopy. On (1 0 0) Cu the interfacial reaction during reflow resulted in a columnar growth of Cu3Sn along Cu [1 0 0] with a special crystallographic relationship of (21¯0)Cu3Sn∥(4¯02)Cuand[122]Cu3Sn∥[010]Cu. In the subsequent solid-state aging new triangular Cu3Sn grains nucleated and grew at the triple junction sites of the interface between Cu and two adjacent Cu3Sn grains.